Electronically-controlled mechanically-damped off-resonant light beam scanning mechanism and code symbol readers employing the same

ABSTRACT

Apparatus for deflecting a light beam, comprising: a scanning element having a base portion, a light beam deflecting portion, and a gap region disposed therebetween. The base portion is anchored with respect to an optical bench to permit the light beam deflecting portion to pivot about a fixed pivot point defined between the base portion and the gap region. The light beam deflecting portion has a natural resonant frequency of oscillation about the fixed pivot point and is mechanically-damped at the gap region. A permanent magnet and right beam deflating portion are mounted on the light beam deflecting portion. A magnetic-field producing coil produces a force field that interacts with the permanent magnet and forces the light beam deflecting portion to oscillate about the fixed pivot point at a controlled frequency of oscillation that is substantially different from the natural resonant frequency of oscillation of the light beam deflecting portion.

RELATED CASES

This Application is a Continuation of U.S. application Ser. No.09/895,808 filed Mar. 13, 2001, now U.S. Pat. No. 6,874,689 which is acontinuation of Ser. No. 08/931,691 filed Sep. 16, 1997, now U.S. Pat.No. 6,227,450; which is a Continuation-in-part of: application Ser. No.08/916,694 filed Aug. 22, 1997, now U.S. Pat. No. 5,905,248; applicationSer. No. 08/869,164 filed Jun. 4, 1997, now U.S. Pat. No. 5,992,752;application Ser. No. 08/846,219 filed Apr. 25, 1997, now U.S. Pat. No.6,076,733; application Ser. No. 08/838,501 filed Apr. 7, 1997, now U.S.Pat. No. 5,869,819; application Ser. No. 08/820,540 filed Mar. 19, 1997,now U.S. Pat. No. 6,068,188; application Ser. No. 08/753,367 filed Nov.25, 1996, now abandoned; application Ser. No. 08/645,331 filed May 13,1996 now U.S. Pat. No. 5,844,227; application Ser. No. 08/615,054 filedMar. 12, 1996, now U.S. Pat. No. 6,286,760; application Ser. No.08/573,949 filed Dec. 18, 1995, now abandoned; application Ser. No.08/292,237 filed Aug. 17, 1994, now U.S. Pat. No. 5,808,285; applicationSer. No. 08/365,193 filed Dec. 28, 1994, now U.S. Pat. No. 5,557,093;application Ser. No. 08/293,493 filed Aug. 19, 1994, now U.S. Pat. No.5,525,789; application Ser. No. 08/561,479 filed Nov. 20, 1995, now U.S.Pat. No. 5,661,292; application Ser. No. 08/278,109 filed Nov. 24, 1993,now U.S. Pat. No. 5,484,992; application Ser. No. 08/489,305 filed Jun.9, 1995, now abandoned; application Ser. No. 08/476,069 filed Jun. 7,1995, now U.S. Pat. No. 5,591,953; application Ser. No. 08/584,135 filedJan. 11, 1996, now U.S. Pat. No. 5,616,908; application Ser. No.08/651,951 filed May 21, 1996, now U.S. Pat. No. 5,874,721; applicationSer. No. 08/489,305 filed Jun. 9, 1995, now abandoned; application Ser.No. 07/821,917 filed Jan. 16, 1992, now abandoned; application Ser. No.07/583,421 filed Sep. 17, 1990, now U.S. Pat. No. 5,260,553, andapplication Ser. No. 07/580,740 filed Sep. 11, 1990, now abandoned. Eachsaid patent application is assigned to and commonly owned by MetrologicInstruments, Inc. of Blackwood, N.J., and is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to laser scanning systems and moreparticularly, to electronically-controlled damped off-resonantmechanisms for reliably scanning laser beams during bar code symbolreading operations and the like.

2. Brief Description of the Prior Art

Laser scanning bar code symbol scanners are widely used to read bar codesymbols on products and packages for identification purposes. Manydifferent techniques exist for scanning laser beams across objects.

One commonly used beam scanning technique involves driving a resonantelement bearing a mirror into oscillatory motion within a plane, while alaser beam is directed incident the mirror surface. As the resonantelement oscillates, so too does the mirror, causing the incident laserbeam to be scanned across a scanning field of substantially planarextent, as well as a bar code symbol disposed therewithin. In general,laser light reflected from the scanned bar code symbol is collected anddetected to produce an electrical signal representative of the scannedsymbol. Ultimately, the electrical signal is processed in order todecode the scanned symbol and produce symbol character datarepresentative of the decoded symbol.

In U.S. Pat. Nos. 5,168,149, 5,280,165, 5,374,148 and 5,581,067, severaldifferent scanning mechanisms are disclosed, in which strips made ofMylar™ or Kapton™ plastic material are used to realize resonant scanningelements. While such prior art scanning elements are durable, they arenot without their shortcomings and drawbacks.

Such prior art laser scanning mechanisms are generally massive and largein comparison to the size of the scanning mirror supported thereby.Prior art laser scanning mechanisms are generally difficult to produce,expensive to manufacture, difficult to precisely tune, and typicallyrequire an anti-shock mechanism to protect the scanning element fromdamage when dropped.

Addressing the shortcomings and drawbacks associated with theabove-described scanning mechanism, Applicants hereof have attempted toconstruct a laser beam scanning mechanism, in which a thin strip ofKapton™ film, anchored at its base end and supporting a miniature mirrorand a ferrite magnet on its free end, is driven in an off-resonant modeof operation in order to scan a laser beam incident the mirror. Whilelaboring long and hard, Applicants have been unable to consistentlymanufacture in large volume and at low cost, a laser beam scanningmechanism based on such prior art design principles, without seriouslysacrificing the operation and performance thereof.

Consequently, hitherto, Metrologic's ScanQuest® Laser Scanning Engine(Models 4110 and 4120), in which the above-described scanning mechanismis employed, could not be manufactured in high volume or at low cost.

Therefore, there is a great need in the art for an improved laserscanning mechanism which avoids the shortcomings and drawbacks of priorart laser beam scanning apparatus and methodologies.

OBJECTIVES AND SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean improved laser beam scanning apparatus that avoids the shortcomingsand drawbacks of prior art technologies.

A further object of the present invention is to provide such a laserbeam scanning apparatus in the form of an electronically-controlledmechanically-damped off-resonant laser beam scanning mechanismcomprising an etched scanning element having a small flexible gap regionof closely-controlled dimensions disposed between an anchored baseportion and a laser beam deflecting portion.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the resonant frequency of oscillation ofthe laser beam deflecting portion relative to the anchored base portionis determined by the closely controlled dimensions of the flexible gapregion set during manufacture.

A further object of the present invention is to provide such a laserbeam scanning mechanism, in which the resonant frequency of oscillationof the scanning element is tuned by adjusting the thickness and width ofthe flexible gap region.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the physical dimensions of the flexible gapregion are closely controlled by using chemical-etching techniquesduring manufacture.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the etched scanning element is manufacturedby chemically etching a double-sided copper clad sheet consisting of apolyamide base material laminated between ultra-thin copper sheets.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which a permanent magnet is mounted on the rearsurface of the laser beam deflecting portion, and a laser beamdeflecting element is mounted on the front surface of the laser beamdeflecting portion.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the base portion is securely fixed to anoptical bench and the laser beam deflecting portion is forced tooscillate substantially away form the natural resonant frequency of thescanning element, by a reversible electromagnet disposed in closeproximity to a permanent magnet mounted to the rear surface of the laserbeam deflecting portion.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the natural harmonic (i.e., resonant)frequency of the laser beam deflecting portion about the anchored baseportion is mechanically-damped by adding a thin layer of flexible rubbermaterial to the gap region of the scanning element during manufacture,and the laser beam deflecting portion is forcibly driven by a reversibleelectromagnet operated at a forcing (i.e., driving) frequency tunedsubstantially away (i.e., off) from the natural resonant frequency ofthe laser beam deflecting portion.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the steady-state frequency of oscillationof the laser beam deflecting portion is determined by the frequency ofpolarity reversal of the electromagnet, which is electronicallycontrolled by the polarity of the electrical current supplied to theinput terminals of the magnet coil of the reversible electromagnet.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the driving or forcing frequency of theelectromagnet is selected to be at least ten percent off (i.e., greateror less than) the natural resonant frequency of the laser beamdeflecting portion.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the steady-state (i.e., controlled)frequency of oscillation of the scanning element can be set at the timeof manufacture to be any one of a very large range of values (e.g.,25-125 Hz) for use in both low-speed and high-speed laser scanningsystems.

Another object of the present invention is to provide such a laser beamscanning mechanism having ultra-low power consumption, and a lowoperating current.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the angular sweep of the laser beamdeflecting element is about thirty degrees (i.e., ±15° degrees) measuredwith respect to the point of pivot about the anchored base portion ofthe scanning element of the present invention.

Another object of the present invention is to provide such a laser beamscanning mechanism, in which the scanning element and electromagnet aremounted within an ultra-compact housing having integrated stops forlimiting the sweep that the scanning element is permitted to undergoduring operation.

Another object of the present invention is to provide such a laser beamscanning module for use in hand-held, body-wearable, and stationary barcode symbol reading systems having a 1-D laser scanning pattern.

Another object of the present invention is to provide a 2-D laserscanning module constructed from the assembly of a pair of 1-D laserscanning modules of the present invention.

Another object of the present invention is to provide a 2-D laserscanning module, in which the 2-D laser scanning pattern producedthereby is electronically-controlled by electronic circuitry used toproduce current drive signals provided to the electromagnetic coils ofthe reversible electromagnets mounted within the laser beam scanningmodules of the present invention.

Another object of the present invention is to provide a novel method formanufacturing scanning elements used in the laser beam scanningmechanisms and modules of the present invention.

A further object of the present invention is to provide ahand-supportable laser scanning bar code symbol reader employing thelaser beam scanning module of the present invention, in order toselectively produce either a 1-D or 2-D laser scanning pattern forreading 1-D or 2-D bar code symbols, respectively.

A further object of the present invention is to provide a portable data(transaction) terminal having the laser beam scanning module of thepresent invention integrated therewith, in order to produce either a 1-Dor 2-D laser scanning pattern by manual selection, or bar code symbolprogramming, for reading 1-D or 2-D bar code symbols, respectively.

A further object of the present invention is to provide a body-wearabletransaction terminal having the laser beam scanning module of thepresent invention integrated therewith, in order to selectively produceeither a 1-D or 2-D laser scanning pattern for reading 1-D or 2-D barcode symbols, respectively.

A further object of the present invention is to provide a body-wearableInternet-based transaction terminal having the laser beam scanningmodule of the present invention integrated therewith, in order to read1-D or 2-D URL-encoded bar code symbols.

A further object of the present invention is to provide a 2-D laserscanning bar code symbol reader, in which a real-time analysis of thebar code symbol structure being scanned is used to automatically set theresolution of the 2-D laser scanning pattern in order to scan 2-D barcode symbols in an optimal manner.

These and other objects of the present invention will become apparenthereinafter and in the Claims To Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, the appendedfigure drawings should be read in conjunction with the followingDetailed Description of the Illustrative Embodiments, in which:

FIG. 1A is a schematic diagram of the laser beam scanning mechanism ofthe present invention, showing the anchored base portion thereof mountedon a support structure of an optical bench and the laser beam deflectingportion, extending from the base portion, bearing a light beamdeflecting element on its front surface and a magnetic element on itsrear surface for interaction with an externally generated magnetic forcefield produced by a miniature electromagnet driven by an electricalpulse train having a frequency which is controlled by an electronicsignal generation circuit;

FIG. 1B is a cross-sectional view of the laser beam scanning mechanismof the present invention, taken along line 1B-1B of FIG. 1A;

FIG. 1C is a cross-sectional view of the resonant scanning mechanism ofthe present invention, taken along line 1C-1C of FIG. 1A;

FIG. 2A is a perspective view of a chemically-etched sheet ofdouble-sided copper-clad base material used to mass-manufacture thescanning element of the present invention;

FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2Ashowing a portion of the double-sided copper-clad base material that hasnot been chemically etched;

FIG. 2C is a cross-sectional view taken along line 2C-2C of FIG. 2Ashowing a portion of the double-sided copper-clad base material that hasbeen chemically etched so as to form seven rows of three scanningelements therefrom;

FIG. 3A is a schematic diagram of a first illustrative embodiment of aminiature laser scanning engine realized upon an optical bench using alaser diode, a stationary folding mirror, an electromagnetic coil, andthe laser beam scanning mechanism of shown in FIG. 1A;

FIG. 3B is a schematic diagram of an electronic circuit for producingthe voltage drive signal applied to the magnetic field producing coil inthe scan engine of FIG. 3A.

FIG. 4A is a perspective view of a second illustrative embodiment of aminiature laser beam scanning module realized using an ultra-compactplastic housing in which the laser beam scanning mechanism of thepresent invention shown in FIG. 1A is mounted;

FIG. 4B is a perspective view of a subcomponent of the scanningmechanism of the second illustrative embodiment which is snap connectedto the housing shown in FIG. 4A and functions to delimit the angularexcursion under which the scanning element thereof is permitted to goduring scanner operation;

FIG. 5 is a perspective diagram of a third illustrative embodiment ofthe present invention, in which a pair of miniature laser beam scanningmodules shown in FIG. 4A are configured on an optical bench to form anultra-compact laser beam scanning device capable of producing either a1-D or 2-D raster-type laser scanning pattern by manually depressing anexternally-mounted button or switch, or by reading a predetermined barcode symbol encoded to automatically induce a particular mode of scanneroperation;

FIG. 6 is a schematic diagram of the circuitry for producingsynchronized drive signals for the ultra-compact 1-D/2-D laser scanningdevice shown in FIG. 5, and automatically setting the resolution of the2-D laser scanning pattern produced therefrom in response to a real-timeanalysis of scanned 2-D bar code symbols;

FIG. 7A is a schematic representation of the output clock signal used tosynchronize the current drive signal supplied to the electromagneticcoil of the X-axis laser beam scanning module integrated into theultra-compact laser scanning device of FIG. 5;

FIG. 7B is a schematic representation of the drive current signalsupplied to the electromagnetic coil of the X-axis laser beam scanningmodule of the ultra-compact laser scanning device of FIG. 5;

FIG. 7C is a schematic representation of the voltage signal used todrive the electromagnetic coil of the Y-axis laser beam scanning moduleof FIG. 5 when a two-line raster scanning pattern is to be produced;

FIG. 7D is a schematic representation of the voltage signal used todrive the electromagnetic coil of the Y-axis laser beam scanning moduleof FIG. 5 when an eight-line raster scanning pattern is to be produced;

FIG. 7E is a schematic representation of the voltage signal used todrive the electromagnetic coil of the Y-axis laser beam scanning moduleof FIG. 5 when an eight-line raster scanning pattern is to be produced;

FIG. 8A1 is a plan view of the 1-D laser scanning pattern produced fromthe graphical representation of a one-dimensional (1-D) laser scanningpattern produced from the laser scanning module shown in FIGS. 5 through7E, integrated within a hand-supportable bar code symbol reader;

FIG. 8A2 is an elevated side-view of the one-dimensional (1-D) scanningpattern produced from the laser scanning module of the present inventionshown in FIGS. 5 through 7E, shown integrated within a hand-supportablebar code symbol reader;

FIG. 8B is an elevated side-view of a two-line raster scanning patternproduced from the laser scanning module of the present invention shownin FIGS. 5 through 7E, shown integrated within a hand-supportable barcode symbol reader;

FIG. 8C is an elevated side-view of a four-line raster scanning patternproduced from the laser scanning module of the present invention shownin FIGS. 5 through 7E, shown integrated within a hand-supportable barcode symbol reader;

FIG. 8D is an elevated side-view of a eight-line raster scanning patternproduced from the laser scanning module of the present invention shownin FIGS. 5 through 7E, shown integrated within a hand-supportable barcode symbol reader;

FIG. 9A is a schematic diagram of the hand-supportable multi-scanpattern generating bar code symbol reader of the present invention shownbeing used in its hands-free (i.e., stand-supported) mode of operation;

FIG. 9B is a schematic diagram of the hand-supportable multi-scanpattern generating bar code symbol reader of the present invention shownbeing used in its hands-free (i.e., stand-supported) mode of operation;

FIG. 10 is a perspective view of a portable Internet-based datatransaction terminal according to the present invention, in which thelaser beam scanning module of FIGS. 5 and 6 is integrated therewith forscanning 1-D and 2-D bar code symbols; and

FIG. 11 is a perspective view of a body-wearable Internet-based datatransaction terminal according to the present invention, in which thelaser beam scanning module of FIGS. 5 and 6 is integrated therewith forscanning 1-D and 2-D bar code symbols.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

The illustrative embodiments of the present invention will be describedwith reference to the figure drawings wherein like elements andstructures are indicated by like reference numbers.

Overview of the Laser Beam Scanning Mechanism of the Present Invention

In FIG. 1A, the laser beam scanning mechanism of the present invention 1is shown having a base portion 2 mounted (i.e., anchored) on a supportstructure 3 of an optical bench 4, and a laser beam deflecting portion 5extending from the base portion, with a flexible gap portion 6 disposedtherebetween.

As shown, the laser beam deflecting portion 5 bears a light deflectingelement 7 on its front surface and a thin permanent magnet element 8mounted on its rear surface. The light deflecting element 7 can berealized in a number of different ways, namely: as a light reflectiveelement such as a mirror; as a light diffractive element such as areflection or transmission hologram (i.e., HOE); as a light refractiveelement such as a lens element; or as any other type of optical elementcapable of deflecting a laser beam along an optical path as the laserbeam deflecting portion 5 is oscillated about a fixed pivot point 9defined at the interface between the anchored base portion and flexiblegap portion of the scanning element. Light deflecting element 7 andmagnetic element 8 can be mounted to the scanning element using anadhesive, or other fastening technique (e.g., soldering) well known inthe art. In the illustrative embodiments disclosed herein, the laserbeam deflecting portion 5 is oscillated about its fixed pivot point byproducing a reversible magnetic force field (e.g., of about 260 Gauss)directed against the permanent magnet 8 (e.g., 20/1000^(th) thick)mounted on the rear surface of the laser beam deflecting portion.

As shown in FIGS. 1A, 1B and 1C, the scanning element of the presentinvention has a laminated construction, wherein: the anchored baseportion 2 and the laser beam portion 5, each consist of a thin layer ofKapton™ polyamide 16 sandwiched between a pair of thin layers of copper17A and 17B, and 18A and 18B, respectively; and the flexible gap portion6 consisting of the thin layer of Kapton™ (polyamide) plastic materialand a thin layer of mechanically-damping film material, such asscreenable silicone rubber (e.g., General Electric SLA 74015-D1), havinga suitable durometer measure, e.g., Shore A40. Notably, the thin layerof polyamide in the anchored base portion 2, the flexible gap portion 6and the laser beam deflecting portion 6 is realized as a single unitarylayer having a uniform thickness across these individual portions of thescanning element. The copper layers on opposite sides of the anchoredbase portion, the flexible gap portion and the laser beam deflectingportion of the scanning element are discrete elements of uniformthickness realized by precisely-controlled chemical-etching of thecopper and polyamide layers during particular stages of the scanningelement fabrication process described below.

Fabrication of the Scanning Element of the Present Invention

The preferred method of fabricating the flexible scanning element of thepresent invention will be described with reference to FIGS. 2A,2B and 2Cin the Drawings.

The first step of the fabrication method involves providing a sheet ofbase material 20, in which sheets of thin copper foil material 21A and21B are laminated onto both front and back surfaces of a 12″×12″ sheetof Kapton™ polyamide film material 22 using a epoxy adhesive. Suitablecopper-laminated base material (“base material”) can be obtained fromTechetch, Inc., of Plymouth, Mass. The cross-sectional nature of thisbase material is shown in FIG. 2B.

Both sides of the 12″×12″ sheet of base material 20 are screen-printedwith a pattern of copper-protective ink (“photo-resist”). Thecopper-protective pattern is structured so that it covers those areas ofthe sheet where the copper elements associated with the anchorable baseportion 2 and the laser beam deflecting portion 5 of many scanningelements are to be formed on the polyamide layer in aspatially-registered manner, as shown in FIGS. 2A and 2C. Those areasnot covered by the copper-protective pattern (i.e., where the gapportions of the scanning elements are to be formed and scanning elementmounting hole 25) are susceptible to the copper-etchant to be used in asubsequent etching stage. After the copper-protective pattern isprinted, the sheet is exposed to the copper-etchant by dipping the sheetin a reservoir of the same. Thereafter, the chemically-etched sheet,having etched copper surfaces 23A and 23B, is rinsed in a conventionalmanner. As this stage of the fabrication process, the copper elementsassociated with the anchorable base portion and the laser beam portionof 400 scanning elements are formed on the 12″×12″ sheet in aspatially-registered manner; also, the gap portions of the scanningelements made from polyamide material are also formed betweencorresponding base and laser beam deflecting portions.

The next stage of the fabrication process involves screen-printing apattern of polyamide-protective ink on the chemically-etched sheet. Thepolyamide-protective pattern is structured so that it covers those areasof the sheet where the polyamide gap portions 6 have been previouslyformed, as well as very thin strips or string-like elements (e.g.,called “stringers”) between the copper elements associated with theanchorable base portion and the laser beam portion of neighboringscanning elements. Those areas of exposed polyamide not covered by thepolyamide-protective pattern described above (e.g., scanning elementmounting hole 25) are susceptible to the polyamide-sensitive etchantthat is to be used in a subsequent etching stage. After thepolyamide-protective pattern is printed, the sheet is exposed to thepolyamide-etchant by dipping the partially-etched sheet in a reservoirof the same. Thereafter, the etched sheet is rinsed in a conventionalmanner. At this stage of the fabrication process, the polyamide elementsassociated with the gap portion of the 400 scanning elements are formedon 12″×12″ sheet, along with the copper elements associated with thebase portions and laser beam deflecting portions thereof. Each scanningelement is suspended with respect to its neighboring scanning element byway of the formed “stringers” 24 which can easily be broken by gentlypulling a fabricated scanning element from the nested matrix of scanningelements formed in the etched copper-cladded sheet described above.

While suspended within the nested matrix, a thin layer of GE silicone(Durometer of Share A 40) of about 0.01 inch thick is screened onto asingle surface of the gap region of each scanning element. The functionof this silicone film layer is to provide mechanical damping mechanismto the resonant scanning element being fabricated.

Once fabricated in the manner described above, the permanent (ferrite)magnets 8 and light deflecting (mirror) elements 7 can be attached tothe laser beam deflecting portions of the etched scanning elements usingCNC-based robotic machinery well known in the art. In addition, thecompletely fabricated scanning elements can then be mounted to theiroptical benches (or mounting brackets) using CNC-based machinery wellknown in the art.

Notably, while the above-described process involves treating singlesheets of base material, it is understood that in alternativeembodiments of the present invention, a roll of base material can beused (instead of sheets) and treated using a continuous version of theabove-described fabrication process.

Tuning the scanning element described above is relatively easy. It hasbeen determined that the natural resonant frequency of oscillation ofthe light beam deflecting portion 5 is functionally related to: thethickness of the layer of flexible material 16; the physical dimensionsof the flexible gap portion 6; the total mass of the laser beamdeflecting portion, including the laser beam deflecting element (e.g.,mirror) 7 and the permanent magnet 8. For a given permanent magnet,mirror element and base material (e.g., double-sided copper-cladpolyamide), the natural resonant frequency of the laser beam deflectingportion about the fixed pivot point 9 can be precisely controlled bycontrolling the physical dimensions of the flexible gap region 6 duringthe copper etching stage of the scanning element fabrication process(i.e., printing the copper-protective and polyamide-protective pattern).This technique enables tuning the scanning element over a fairly broadrange of operation. For a greater degree of tuning, it might bedesirable or necessary to use a different base material, in which thethickness of the polyamide layer is thicker (where a higher scanningfrequency is required), or thinner (where a lower scanning frequency isrequired).

While sophisticated mathematical models of the scanning element can becreated to assist in the design process of the scanning element hereof,it has been found that straight forward experimentation can be used todetermine the gap dimensions for a desired natural operating frequency.As the forced frequency of operation is the “operating frequency” of thescanning mechanism, the designer will start with the desired operatingfrequency (i.e., set by scanning speed requirements, bar code symbolresolution, signal processing limitations, etc.) and figure out what thenatural resonant frequency of the scanning element must be (e.g., atleast 10% away from the forced frequency of operation). Knowing theapproximate range of the natural resonant frequency of the scanningelement under design, the designer can then experiment (or model) in astraight forward manner to determine the physical dimensions required toattain the desired natural frequency of oscillation for a scanningelement fabricated from a particular base material.

Using the above-described fabrication technique, scanning elements havebeen fabricated with natural resonant frequencies of operation withinthe range of about 50 Hz to about 250 Hz.

In the Table I below, the resonant frequencies are listed for a numberof different scanning elements (1) fabricated using base material havinga polyamide thickness of 0.001 inches, and 2.0 ounce double-sided coppercladding, and (2) having a laser beam deflecting portion (including amirror and permanent magnet) with a total mass of about 0.11 grams(i.e., where the ferrite magnet has a mass of 0.04 grams and mirrorhaving mass of 0.03 grams).

Double sided copper clad  2.0 oz Polyamide layer thickness 0.001 inchMass of Ferrite Magnet  0.04 grams Mass of Mirror Element  0.03 gramsTotal Mass of Light Beam  0.11 grams Deflecting Portion Gap RegionHeight 0.160 inch Thickness of Silicon  0.01 inch Damping Film LayerApplied over one side of Gap Region Durometer of Silicone Shore A 40Damping Film Layer RESONANT GAP REGION FREQUENCY (Hz) WIDTH (Inch) 25.065 26.5 .060 28.0 .055 29.5 .050 31.0 .045 32.5 .040 34.0 .035 35.5.030 37.0 .025 38.5 .020 40.0 .015

In the Table II below, the resonant frequencies are listed for a numberof different scanning elements (1) fabricated using base material havinga polyamide thickness of 0.003 inches, and 2.0 ounce double-sided coppercladding, and (2) having a laser beam deflecting portion (including amirror and permanent magnet) with a total mass of about 0.11 grams(i.e., where the ferrite magnet has a mass of 0.04 grams and mirrorhaving mass of 0.03 grams).

Double sided copper clad  2.0 oz Polyamide layer thickness 0.003 inchMass of Ferrite Magnet  0.04 grams Mass of Mirror Element  0.03 gramsTotal Mass of Light Beam  0.11 grams Deflecting Portion Gap RegionHeight 0.160 inch Thickness of Silicon  0.01 inch Damping Film LayerApplied over one side of Gap Region Durometer of Silicone Share A 40Damping Film Layer RESONANT GAP REGION FREQUENCY (Hz) WIDTH (Inch) 75.065 79.5 .060 84 .055 88.5 .050 93 .045 97.5 .040 102 .035 106.5 .030111 .025 115.5 .020 120 .015 124.5 .010Laser Beam Scanning Module of the First Illustrative Embodiment

In FIG. 3A, a laser beam scanning mechanism of the first illustrativeembodiment is shown realized on an optical bench 26 of planardimensions. Magnetic-field producing coil (i.e., electromagnetic coil)11 is supported upon a first projection (e.g., bracket) 27 which extendsfrom the optical bench. The scanning element of the present inventiondescribed above is mounted upon a second projection 28 which extendsfrom the optical bench. The scanning element of the present inventiondescribed above is mounted upon a second projection 28 which extendsfrom the optical bench. The permanent magnet 8 is placed in closeproximity with the magnetic-field producing coil 11, as shown in FIG.3A. A visible laser diode (VLD) 29 is mounted adjacent the scanningelement (by way of bracket 30) so that its output laser beam 31 isdirected towards a beam folding mirror 32, supported from a thirdprojection (bracket) 33 extending from the optical bench. The laser beamreflected off the beam folding mirror 32 is directed towards the laserbeam deflecting portion 5 of the scanning element and reflects outwardlyalong the projection axis 34 of the scanning module. The scanningelement is forced into oscillatory motion by driving the electromagneticcoil 11 with a voltage signal having a frequency substantially off theresonant frequency of the scanning element (e.g. , by at least 10%).

In the preferred embodiment, the electromagnetic coil 11 is driven in apush-pull mode, in which the magnetic polarity reverses periodically atrate determined by the amplitude variation of the voltage signal appliedacross the terminals 34 of the electromagnetic coil 11. A suitablevoltage waveform for driving the electromagnetic coil 11 in the laserbeam scanning mechanism of FIG. 3A can be generated by the electroniccircuit 12 shown in FIG. 3B. As shown, electronic circuit 12 comprises:a clock generator 36 for producing a clock signal having a frequency f₁determined by an external RC network, comprising resistor R andcapacitor C, where the clock frequency thereof f₁ is determined by theexpression f₁=1/2.07 RC; a divider circuit 37 for dividing clockfrequency f₁ by a factor of twenty (20) to produce f₂=f₁/20; and aconventional push-pull current drive integrated circuit (IC) chip 38connected to magnetic-field producing coil 11 in anelectrically-floating manner (i.e., not connected to electrical ground)as shown in FIG. 3B. The RC network is used to set the frequency of thedrive current in coil 11, which sets the scan rate (e.g., sweeps or scanlines per second) of the scanning mechanism.

In the illustrative embodiment, where for example the resonant frequencyof the scanning element is about 36 Hz, the controlled frequency of thelaser beam scanning mechanism should be set at about 28 Hz or 41Hz(e.g., ±7 Hz about the resonant frequency) which, in turn, determinesthe scan rate of the laser scanning module to be 56 or 82 scan lines persecond, respectively. The controlled frequency of the scanning mechanismis set by adjusting the frequency of the drive current signal in coil11. The scanning mechanism of the present invention scan be designed toprovide scan rates higher than 250 scan lines per second (e.g., by usinga thicker polyamide layer and/or narrowing the gap region of thescanning element.

Laser Beam Scanning Module of the Second Illustrative Embodiment

In FIGS. 4A and 4B, a second illustrative embodiment of a miniaturelaser beam scanning module 40 is shown realized using an ultra-compactplastic housing 41, in which the electromagnetic coil 11 and the laserbeam scanning mechanism of FIG. 1A are mounted. As shown, plastichousing 41 comprises a bottom plate 41A, side walls 41B and 41Cextending from the base plate, and a surface 41D for mounting theanchorable base portion 2 of the scanning element hereof thereto.Housing 41 also is provided with a recess 42 in side wall 41C, withinwhich the magnetic-field producing coil 11 can be mounted in a press-fitmanner. When assembled, the scanning element extends towards the centralaxis of the magnetic-field producing coil 11 so that the permanentmagnet 8 is closely positioned adjacent one end of the coil, while theother end thereof, mounted on a support post 43 in recess 42, is mountedthereto. The terminals of the magnetic-field producing coil can bepassed through small holes drilled in side wall 41 C. Bottom plate 41Ahas a pair of holes 45A and 45B formed therein for receiving the ends ofposts 46A and 46B which extend from cover plate 47. A projection 48 oncover plate 47 snaps into hole 49 in the top surface 41E of the sidewall 41B, while mounting posts 46A and 46B snap within holes 45A and45B, respectively. When the cover 47 is assembled with the plastichousing 41, the posts 46A and 46B straddle the flexible gap portion 6 ofthe scanning element and function to limit the maximum angular swingthereof if and when the scanning mechanism is subjected to excessiveexternal forces as might be experienced when dropped to the ground. Insuch an assembled configuration, the laser beam scanning module has ascanning aperture 50, through which the laser beam can be swept alongeither a 1-D or 2-D scanning pattern. Preferably, all of the componentsof the housing described above are fabricated using injection moldingtechnology well known in the art.

As shown, the bottom plate of the module includes a set of bottomprojections 51A, 51B, 51C and 51D which can be used to mount the plastichousing with respect to a primary optical bench or other surface withina host system incorporating the same.

Laser Beam Scanning Module of the Third Illustrative Embodiment

A third illustrative embodiment of the present invention is shown inFIG. 5. In this illustrative embodiment, a pair of miniature laser beamscanning modules 40A and 40B, described in detail above, and visiblelaser diode (VLD) 29 are configured onto an optical bench 53 in order toform an ultra-compact laser beam scanning device capable of selectivelyproducing a 1-D or 2-D (raster-type) laser scanning pattern under thecontrol of electronic circuitry 54. The optical bench 53 can be mountedwithin a hand-held scanner housing, a countertop housing, or any otherhousing geometrically adapted to a particular application. As shown inFIG. 5, the optical bench 53 allows the modules 40A and 40B to bemounted relative to each other so that the scanning aperture 5A of thefirst module is orientable along the x-axis of the scanning field, whilethe scanning aperture 5B of second module is orientable along the y-axisthereof. In some applications, it might be desired to provide theoptical bench with beam folding mirrors in order to fold the producedscanning beam in a particular manner. In the illustrative embodiment,the x direction scanning element undergoes a maximum angular excursionof about ±15° about its non-deflected position, whereas the maximumangular excursion for the y-direction scanning element is about ±1.5°about the non-deflected position thereof.

As shown in FIG. 6, the function of electronic circuitry 54 is toproduce drive signals for synchronously driving the laser scanningmodules 40A and 40B so that 1-D or 2-D scanning patterns are producedunder electronic control. This circuitry can be realized on a smallprinted circuit (PC) board attached to the optical bench 53 or elsewherewithin the host system housing.

In the illustrative embodiment, a push-pull drive IC 56 is used toproduce a current drive signal for the x-axis magnetic-field producingcoil 11A. The clock frequency of the clock signal 57 produced frompush-pull drive circuit 56 is set by an external resistor/capacitatornetwork 58 (R1 and Cl) connected to a 5 Volt power supply in a mannerwell known in the art. The output clock frequency shown in FIG. 7Aserves as a base or reference signal for the operation of circuit 54. Asshown, the output clock signal is provided as input to a synchronous(4-bit) binary counter 60 which produces a plurality of output clocksignals having different clock rates (e.g., 2, 4, 8, etc.) In turn,these output clock signals, along with a DC signal, are provided asinput signals to a multi-channel data selector/multiplexer 61 (e.g.,whose control or gating signals are provided by the system controller 62of the host system (e.g., hand-held bar code symbol reader, countertopscanner, vending machine, etc.) 63. The single output of thedata-selector/multiplexer 61 is provided as input to an inverter 69which is used to drive a transistor (Q1) 65 through a resistor R2connected to the base thereof, with the transistor emitter connected toelectrical ground. In turn, the collector and emitter junction of thetransistor 65 are connected in series with a current limiting resistorR3, a y-axis magnetic-field producing coil 11B and the 5 Volt powersupply.

In the illustrative embodiment, the system controller 62 is operablyconnected to the symbol decoding module 64 of the host system 63.Typically, the symbol decoding module is a programmed microprocessorcapable of decoding 1-D and 2-D bar code symbols usingautodiscrimination techniques and the like. An exemplary systemarchitecture for the host system 63 is described in great detail in U.S.Pat. Nos. 5,260,553, 5,340,971, and 5,557,093, incorporated herein byreference. During decode processing, the symbol decoding module 64carries out one more 2-D decoding algorithms, each embodying“Scan-Pattern Optimization Control Logic”. According to such controllogic, if during the 2-D decoding process, a bar code symbol is decoded,then the decoding module proceeds to determine how many rows of scandata are contained in the 2-D bar code symbol. This is achieved byreading the “row” indication field in the decoded line of scan data anddetermining the number of rows within the scanned 2-D bar code symbol.When this information is recovered by the symbol decoding module, it isthen provided to the system controller 62. In turn, the systemcontroller uses this information to generate a control signal for thedata-selector/multiplexer 61. The control signal selects a signal (atthe multiplexer's input) which drives the y-axis magnetic-fieldproducing coil 11B in an manner such that the 2-D bar code symbol isoptimally scanned.

For example, if the symbol decoding module detects a 1-D bar codesymbol, then the system controller will automatically produce a controlsignal that causes the multiplexer 61 to select a DC voltage, therebycausing the y-axis magnetic-field producing coil 11B to remain pinneddown, and prevented from deflecting the laser beam along the y-axis ofthe scanning beam.

If the symbol decoding module 64 detects a “Post-Net” type 2-D bar codesymbol, then the system controller will produce a control signal thatcauses the multiplexer to select a clock signal that causes the y-axismagnetic-field producing coil 11B to produce a 2-line raster scanningpattern. If the symbol decoding module detects a “PDF or equivalent”type 2-D bar code symbol, then the symbol decoder determines how manyrows of data are contained in the PDF code symbol. Based on the numberof rows of data contained within the scanned 2-D bar code symbol, thesystem controller will dynamically generate a control signal that causesthe y-axis magnetic-field producing coil to produce an optimal number ofscan lines in the scanning pattern, related to the number of rows ofdata contained within the scanned code symbol.

If the symbol decoding module determines that the PDF symbol has between2-4 rows of data, then the system controller will produce a controlsignal that causes the multiplexer to select a clock signal that causesthe y-axis magnetic-field producing coil 11B to produce a 2-line rasterscanning pattern. If the symbol decoding module determines that the PDFsymbol has between 5-10 rows of data, then the system controller willproduce a control signal that causes the multiplexer to select a clocksignal that causes the y-axis magnetic-field producing coil 11B toproduce a 4-line raster scanning pattern. If the symbol decoding moduledetermines that the PDF symbol has 11 or more rows of data, then thesystem controller will produce a control signal that causes themultiplexer to select a clock signal that causes the y-axismagnetic-field producing coil 11B to produce an 8-line raster scanningpattern.

During operation of the electronic drive circuitry of FIG. 6, thepush-pull drive IC 56 produces a clock signal 57 as shown in FIG. 7A.Based on this clock signal, a current drive signal shown in FIG. 7B isproduced for driving the x-axis magnetic-field producing coil. As theoperation of the x-axis magnetic-field producing coil 11A is reversible(i.e., its magnetic polarity reverses in response to current directionreversal therethrough), the current direction is referenced about a zeromilliampere (0.0 mA) value. Each time the current drive signal changesdirection through windings of the x-axis magnetic-field producing coil11A, so too does the magnetic polarity of the magnetic-field producedthereby and thus the direction of deflection of the scanning elementalong the x-axis.

To prevent deflection of the laser beam along the y-axis, and thuscreate a 1-D scanning pattern, the system controller will select a DCvoltage at multiplexer 61. The selected DC voltage will forward bias thecurrent drive transistor 65 so that a constant current flows throughy-axis magnetic-field producing coil 11B, pinning the scanning elementof the y-axis scanning module and preventing deflection of the laserbeam along the y-axis in response to base clock signal 57 shown in FIG.7A.

To produce a 2-D laser scanning pattern, the system controller willselect one of the voltage signals shown in FIGS. 7C through 7E fordriving current drive transistor 65 connected to the y-axismagnetic-field producing coil 11B. As illustrated in FIG. 6, wheneverthe amplitude of the selected voltage signal is below a predeterminedthreshold (e.g., 0 Volts), then inverter 69 will produce an outputvoltage which forward biases the current drive transistor 65, causingelectrical current to flow through the y-axis magnetic-field producingcoil and a magnetic field produced in response thereto. Under suchconditions, the y-axis magnetic-field producing coil 11B deflects thelaser beam along the y-axis. When the amplitude of the selected voltagesignal rises above the threshold level, the output of the inverter 69decreases so that the current drive transistor 65 is no longerforward-biased. This condition causes current flow through the y-axismagnetic-field producing coil to cease and the magnetic field therefromto collapse, thereby allowing the scanning element to deflect the laserbeam in the opposite direction.

When the selected control voltage changes polarity, the y-axis coil isonce again actively driven and the scanning element thereof deflected,causing the horizontally deflected laser beam to be deflected in alongthe y-axis. The number of horizontal scan lines produced each time thelaser beam is deflected along the y-axis depends on how slowly theamplitude of the selected control voltage (from the multiplexer) changesas the x-axis magnetic-field producing coil deflects the laser beamalong the x-axis each time the current drive signal shown in FIG. 7Bundergoes a signal level transition from high to low.

Notably, the selected control voltage shown in FIG. 7E allows eighthorizontal scan lines to be created along the x-axis before it undergoesits signal level transition, which in effect triggers the repositioningof the laser beam along the start position of the y-axis. The finishposition along the y-axis depends on the time that the selected controlvoltage remains below the threshold voltage, as well as other factors(e.g., scanning aperture of the modules, host scanner, etc.).

Using the above-described principles of the present invention, clearlyit is possible to produce 2-D raster scanning patterns having a numberof horizontal scan lines that are optimally matched to the number ofrows of data within virtually any 2-D bar code symbol being scanned.

In an alternative embodiment of the present invention, it is possiblefor the symbol decoding module 64 to collect information regarding (i)the number of rows in a scanned 2-D bar code symbol and (ii) the lengthof the data rows. The system controller 62 can then use the row numberinformation to set the number of horizontal scan lines to be produced inthe scanning pattern, while the row length information can be used toset the length of the scan lines by limiting the amplitude of electricalcurrent through the x-axis magnetic-field producing coil 11A.

As shown in FIG. 6, such control can be achieved by controller 62sending a control signal 66 to push-pull drive circuit 56, or an activeelement 67 provided in series with electromagnetic coil 11A for thepurpose of actively controlling the electrical current flowingtherethrough.

In another embodiment of the present invention, it is possible for thesymbol decoding module to collect information regarding (i) the numberof rows in a scanned 2-D bar code symbol, (ii) the length of the datarows, and (iii) count data representative of the distance of the symbolin the scanning volume. The system controller can then use the rownumber information to set the number of horizontal scan lines to beproduced in the scanning pattern, and the row length information andcount data to set the length of the horizontal scan lines (by limitingthe amplitude of electrical current through the x-axis magnetic-fieldproducing coil 11A by current control signal 66). By controlling suchscanning parameters, the system controller of the host system canachieve real-time control over the aspect-ratio of the 2-D scanningpattern.

An advantage of such system functionalities will be to improve thevisibility of the scanned laser beam, and optimize data collectionoperations as the laser beam will only be scanned over regions in spacewhere symbol data is likely present.

In FIGS. 8A1 and 8A2, the laser scanning module of the present inventionis shown being operated in its 1-D Scanning Mode. In this mode, a scanpattern is produced having a single horizontal scan line. In FIGS. 8Bthrough 8D, the laser scanning module is shown being operated indifferent variations of its 2-D Scanning Mode, in which a raster-typescanning pattern is produced. In each of these figures, a differentraster scanning pattern is shown being produced with a different numberof scan lines. Preferably, the particular number of scan lines producedare automatically selected by the system controller of the presentinvention, as described in great detail above.

Scanning mode selection can be realized in a number of different ways.One way would be to mount an external button on the housing of the barcode symbol reader into which the scanning module has been integrated.When this mode selection button is depressed, the reader automaticallyenters a particular scanning mode. Alternatively, scanning modeselection can be achieved by way of reading a predetermined bar codesymbol encoded to automatically induce a particular mode of operation.When a predetermined bar code symbol is read, the scanning moduleautomatically enters the scanning mode represented by the scanned barcode symbol.

Illustrative Embodiments of Bar Code Scanning Systems Embodying Thelaser Scanning Module of the Present Invention

In general, the laser scanning modules of the present invention can beembodied within diverse types of bar code driven systems, includinghand-held bar code symbol readers, body-wearable bar code symbolreaders, fixed counter scanners, transaction terminals, reverse-vendingmachines, CD-juke boxes, etc. In FIGS. 9A through 11, a few illustrativeexamples are shown where such laser scanning modules can be embodied.Such examples are not intended to limit the scope of the presentinvention, but simply illustrate several of the many environments thatthe laser scanning modules of the present invention might be embedded.

In FIGS. 9A and 9B, the laser scanning module of FIG. 5 is shownembodied within a hand-supportable bar code symbol reader 70 of the typedescribed in U.S. Pat. Nos. 5,260,553 and 5,340,971, incorporated hereinby reference. In FIG. 9A, the scanner is shown being used in itshands-on mode of operation. In FIG. 9B the scanner is shown being usedin its hands-free mode of operation, where it is supported within astand 71. In either of these modes of operation, 1-D or 2-D laserscanning patterns 73 can be automatically produced from the bar codesymbol reader in the manner described hereinabove.

In FIG. 10, the laser scanning module of FIG. 5 is shown embodied withina hand-held bar code symbol driven Internet-based access terminal 75. Asshown, the terminal 75 is shown connected to an ISP 76 by way of aradio-base station 77 and wireless link 78 The hand-held Internet AccessTerminal 75 has an integrated GUI-based web browser program, displaypanel 79, touch-screen type keypad 80, and programmed bar code symbolscanner 81 incorporating the laser scanning module of FIG. 5. Thefunction of bar code symbol scanner 81 can be multi-fold: namely: it maybe used to read a bar code symbol 82 that is encoded with the URL of atransaction-enabling Web page to be accessed from a web (http) server 83by the Internet-based Transaction-Enabling System, and produce symbolcharacter data representative thereof; it may be used to read UPC-typebar code symbols in order to access a database connected to the Internet85 by way of a common gateway interface (CGI); or it may be simply usedto read other types of bar code symbols that identify a product orarticle in a conventional manner.

In the illustrative embodiment, the Internet Access Terminal 75 isrealized as a transportable computer, such as the Newton® Model 2000MessagePad from Apple Computer, Inc. of Cupertino, Calif. This device isprovided with NetHopper™ brand Internet Access Software from whichsupports the TCP/IP networking protocol within the Newton MessagePadoperating system. The Newton MessagePad is also equipped with a MotorolaPCMCIA-based modem card 86 having a RF transceiver for establishing awireless digital communication link with either (i) a cellular basestation, or (ii) one or more satellite-base stations connected to theInternet by way of ISP 76 in a manner well known in the globalinformation networking art.

As shown, the entire Newton MessagePad, ScanQuest® laser scanning module75 and auxiliary battery supply (not shown) are completely housed withina rubberized shock-proof housing 87, in order to provide ahand-supportable unitary device. Once the object (e.g., transactioncard) 88 is detected by the object detection field 89, a laser beam 90is automatically projected and swept across the bar code symbol thereon.

In the above-illustrative embodiments, the bar code symbol readingdevice has been either supported within the hand of the operator, upon acountertop surface or the like. It is contemplated, however, that thelaser scanning module of the present invention can be embodied within abody-wearable bar code symbol reader designed to be worn on the body ofan operator as illustrated in FIG. 11. As shown, the body-wearableInternet-based system 91 comprises: a bar code symbol scanning unit 92designed to be worn on the back of the hand, and within which the 1D/2Dlaser scanning module of the present invention is integrated; and aremote unit 93 (i.e., body-wearable RF-based Internet access terminal)designed to be worn about the forearm or foreleg of the operator byfastening thereto using flexible straps or like fastening technology.

In the illustrative embodiment, hand-mounted scanning unit 92 comprises:a light transmission window 94 for exit and entry of light used to scanbar code symbols; a glove 95 worn by the operator for releasablymounting the housing 96 to the back of his or her hand; and a laserscanning bar code symbol reader 97, as described hereinabove withrespect to the other illustrative embodiments of the present invention.

In the illustrative embodiment, the remote unit 93 comprises: an LCDtouch-screen type panel 97; an audio-speaker 98; a RISC-basedmicrocomputing system or platform 99 for supporting various computingfunctions including, for example, TCP/IP, HTTP, and other Internetprotocols (e.g., E-mail, FTP, etc.) associated with the use of anInternet browser or communicator program (e.g., Netscape Navigator orCommunicator, or MicroSoft Explorer programs) provided by the remoteunit; a telecommunication modem 100 interfaced with the microcomputingsystem; and RF transceiver 101 (e.g., employing DFSK or spread-spectrummodulation techniques) also interfaced with the telecommunication modemfor supporting a 2-way telecommunication protocol (e.g., PPP) known inthe art, between the microcomputing system and a remote transceiver 102(described hereinabove) which is interfaced with ISP 103 connected tothe Internet; a (rechargeable) battery power supply 104 aboard theremote housing, for providing electrical power to the components thereinas well as to the bar code symbol reader 97; and a flexible cable 105,for supporting communication between the bar code symbol reader and themicrocomputing platform, and electrical power transfer from the powersupply to the bar code symbol reader. Notably, the remote unit 93 willembody one of the Internet access methods described hereinabove. Themethod used by remote unit 93 (i.e., Internet access terminal) willdepend on the information that is encoded within the bar code symbolscanned by the bar code symbol reader thereof. Preferably, the remoteunit is worn on the forearm of the operator so that the touch-type LCDpanel 97 integrated therewith can be easily viewed during use of thebody-wearable system of the present invention. Thus, for example, whenan URL-encoded bar code symbol is read by the hand-mounted (orfinger-mounted) bar code symbol reader 92, the transaction-enabling Webpage associated with the scanned bar code symbol displayed on the LCDpanel can be easily viewed and interacted with by the operator. Also, inresponse to reading an URL-encoded bar code symbol (i.e., transactionenabled thereby), the operator may be required to manually enterinformation to the Web page being displayed, using the touch-screendisplay panel 97 and pen-computing software, well known in the art.

Having described the illustrative embodiments of the present invention,several modifications readily come to mind.

For example, while the illustrative embodiments have disclosed the useof base sheet material comprising copper laminated onto Kapton™ plasticmaterial during the fabrication of the scanning element hereof, it isunderstood that other types of resilient plastic materials, includingMylar™ plastic material, can be used to manufacture the scanning elementwith suitable results.

Also, in some applications, it might be desirable to configure several1D/2D laser beam scanning modules hereof in relation with each other inorder to generate various types of omnidirectional scanning patterns.

Also, the VLD and its associated beam shaping optics may be integratedwithin any of the module housings disclosed herein in order to producean miniature laser scanner capable of producing 1D and 2D scanningpatterns under electronic control. Such laser scanners can be integratedwithin various types of systems using bar code symbols to drive ordirect host system operation.

It is understood that the laser scanning modules of the illustrativeembodiments may be modified in a variety of ways which will becomereadily apparent to those skilled in the art of having the benefit ofthe novel teachings disclosed herein. All such modifications andvariations of the illustrative embodiments thereof shall be deemed to bewithin the scope and spirit of the present invention as defined by theClaims to Invention appended hereto.

1. Apparatus for deflecting a light beam, comprising: an optical bench;a scanning element of unitary construction having a base portion, alight beam deflecting portion, and a gap region disposed therebetween,said base portion being anchored with respect to said optical bench soas to permit said light beam deflecting portion to pivot about a fixedpivot point defined between said base portion and said gap region, saidlight beam deflecting portion having a front surface and a rear surfaceand being flexibly connected to said base portion by said gap region,said light beam deflecting portion having a natural resonant frequencyof oscillation about said fixed pivot point and beingmechanically-damped at said gap region; a permanent magnet mounted onsaid light beam deflecting portion; a light beam deflecting elementmounted on said light beam deflecting portion, for deflecting a lightbeam falling incident upon said light beam deflecting element; amagnetic-field producing coil disposed adjacent said permanent magnet,for producing a magnetic force field of reversible polarity in thevicinity of said permanent magnet in response to an electrical currentsignal flowing through said magnetic-field producing coil, at anamplitude which varies at a controllable frequency; and an electricalcircuit operably connected to said magnetic-field producing coil, andproducing an electrical voltage signal which causes said electricalcurrent signal to flow through said magnetic-field producing coil andproduce in the vicinity of said permanent magnet, said magnetic forcefield having a polarity which varies in accordance with the amplitudeand frequency of said electrical current flowing through saidmagnetic-field producing coil, whereby said magnetic force fieldinteracts with said permanent magnet and forces said light beamdeflecting portion to oscillate about said fixed pivot point at acontrolled frequency of oscillation that is substantially equal to saidcontrolled frequency and substantially different from said naturalresonant frequency of oscillation of said light beam deflecting portion;and wherein said controlled frequency of oscillation is different inmagnitude than said natural resonant frequency of oscillation by atleast 10% of said natural resonant frequency.
 2. The apparatus of claim1, wherein a light beam incident upon said light beam deflecting elementis periodically deflected as said light beam deflecting portionoscillates about said fixed pivot point at said controlled frequency ofoscillation, creating a one-dimensional scanning pattern for scanningbar code symbols.
 3. The apparatus of claim 2, which further comprises alight beam source for producing a light beam for directing incident uponthe surface of said light beam deflecting portion.
 4. The apparatus ofclaim 1, wherein said light beam deflecting portion, said gap portionand said base portion each comprise a layer of flexible material, andsaid light beam deflecting portion, and said base portion each include apair of metal elements mounted in registration on said layer of flexiblematerial.
 5. The apparatus of claim 4, wherein said natural resonantfrequency of oscillation of said light beam deflecting portion isrelated to the thickness of said layer of flexible material and thedimensions of said gap portion.
 6. The apparatus of claim 1, whereinsaid light beam deflecting element comprises a light reflective elementmounted onto the front surface of said light beam deflecting portion. 7.The apparatus of claim 1, wherein said light beam deflecting elementcomprises a light refractive element mounted onto the front surface ofsaid light beam deflecting portion.
 8. The apparatus of claim 1, whereinsaid light beam deflecting element comprises a light diffractive elementmounted onto the front surface of said light beam deflecting portion. 9.The apparatus of claim 1, wherein said permanent magnet is mounted onsaid rear surface of said light beam deflecting portion, and said lightbeam deflecting element is mounted on said front surface of said lightbeam deflecting portion.
 10. The apparatus of claim 1, wherein saidoptical bench comprises a module having a first wall structure in whichsaid magnetic-field producing coil is mounted, and a second wallstructure to which said base portion is mounted.
 11. The apparatus ofclaim 10, wherein said module further comprises a pair of stops disposedon opposite sides of said gap portion, to restrict the angular rotationof said scanning element about said fixed pivot point.
 12. The apparatusof claim 10, wherein said module comprises a scanning aperture throughwhich said light beam is permitted to be swept as said light beamdeflecting portion oscillates about said fixed pivot point at saidcontrolled frequency of oscillation.
 13. The apparatus of claim 1,wherein said electrical circuit comprises means for setting saidcontrolled frequency.
 14. The apparatus of claim 1, which furthercomprises a light source for producing said light beam directed incidenton said light beam deflecting element.
 15. The apparatus of claim 14,wherein said light source comprises a visible laser diode.
 16. A barcode symbol reading system comprising: said apparatus of claim 1, forproducing a one-dimensional scanning pattern for scanning a bar codesymbol on an object; light collecting means for collecting lightreflected of said scanned bar code symbol; light detecting means fordetecting said collected light and producing scan data indicative of theintensity of said detected light; and scan data processing means fordecode processing said scan data in order to produce symbol characterdata representative of said scanned bar code symbol.